The UK-built Solar Orbiter is preparing to leave Germany, where it has been undergoing final testing, for its launch site at Cape Canaveral in Florida, USA.

Due to launch in February 2020, Solar Orbiter will perform unprecedented close-up observations of the Sun. It will allow scientists to study the Sun in much more detail than previously possible and to observe specific features for longer periods than can be reached by any spacecraft circling the Earth. In addition, Solar Orbiter will measure the solar wind close to the Sun and provide high-resolution images of the uncharted polar regions of the Sun.

The UK is at the heart of this European Space Agency (ESA) mission to uncover the secrets of our planet’s star. The UK has key industrial roles on the spacecraft build and operations and has won 200 million euros worth of contracts, while the UK Space Agency has invested 20 million pounds for the development and build of the instruments and will continue to support them.

Science Minister Chris Skidmore said:

“I am delighted that the UK has played such a leading role in this mission to observe uncharted regions of the Sun. From mobile phones to electricity networks, our scientists will make new discoveries about the impacts of space weather on our daily lives.

“Our commitment to the European Space Agency means UK research and engineering teams will continue to be at the heart of the new space age after we’ve left the EU, creating highly-skilled jobs and supporting our economy.”

Solar Orbiter will carry 10 state-of-the-art instruments. Remote sensing payloads will perform high-resolution imaging of the Sun’s atmosphere — the corona — as well as the solar disk. Other instruments will measure the solar wind and the solar magnetic fields in the vicinity of the orbiter. This will give us unprecedented insight into how the Sun works, and how we can better predict periods of stormy space weather, which are related to coronal mass ejections (CMEs) that the Sun throws towards Earth from time to time.

UK scientists were instrumental in proposing the Solar Orbiter mission to ESA. The UK Space Agency provided funding for four of the ten scientific instruments on board the spacecraft. Imperial College London, the Science and Technology Facilities Council’s RAL Space and UCL led international teams to design and build three instruments, while UCL also contributed to the fourth.

Chris Lee, Chief Scientist at the UK Space Agency, said:

“Solar Orbiter is the most important UK space science mission for a generation, both because of its leading roles for UK science and industry but also because of the crucial information it will give us about living near a star like the Sun. It has never been more important to understand this interaction because of the impact space weather can have on our satellite enabled economy.”

Solar Orbiter, which will take just under two years to reach its initial operational orbit, will follow in the footsteps of NASA’s Solar Parker Probe, which launched in 2018. The two missions will offer complementary perspectives of the Sun — Parker Solar Probe will travel through the Sun’s atmosphere, while Solar Orbiter will observe the surface.

Engineers at Airbus have designed and built the spacecraft to withstand the scorching heat from the Sun that will hit one side, while the other is frozen as the orbit keeps it in shadow. The design is based on ESA’s BepiColombo mission to Mercury, the closest planet to the Sun, which launched in 2018 with significant involvement from UK engineers and scientists.

Ian Walters, Airbus’ Solar Orbiter project manager, said:

“Solar Orbiter has been one of the most challenging and exciting missions we have ever designed and built here at Stevenage. Not only have we engineered a spacecraft that can withstand the intense solar radiation that is 13 times more powerful than that in Earth’s orbit, we have also made it virtually invisible to its sensors so that it can take accurate measurements to enable a step change in the understanding of the Sun.”

The UK’s space sector is going from strength to strength, employing around 42,000 people and carrying out world-class science while growing the economy. The UK continues to be a leading member of ESA, which is independent of the EU.

Gareth Bethell
UK Space Agency

UK involvement:
UK teams from UCL, Imperial College London and the Science and Technology Facilities Council’s RAL Space are involved in 4 out of the 10 instruments. The UK Space Agency is funding the UK involvement.

* SWA (Solar Wind Analyser) uses three sensors and a processing unit to measure the different elements of the solar wind and characterise their behaviour under different solar conditions. As Principal Investigator institution, UCL Mullard Space Science Laboratory (UCL MSSL) led the development of this instrument suite and built one of the sensors.

* MAG (Magnetometer) comprises two sensors located on a deployable boom in the shadow behind the spacecraft body. It measures the interplanetary magnetic field local to the spacecraft: this magnetic field controls the behaviour of all the particles in interplanetary space. The instrument was developed and built at Imperial College London.

* EUI (Extreme Ultraviolet Imager) is a suite of imaging telescopes that will provide images of the hot and cold layers of the solar atmosphere and of the solar corona showing the dynamics in fine detail and providing the link between the solar surface and outer corona. UCL MSSL is a Co-Investigator for this instrument.

* SPICE (Spectral Imaging of the Coronal Environment) is a telescope with a grating spectrograph and two active pixel sensor detectors that will provide images of the solar disk and corona. SPICE will be able to study features both on the surface and out in the corona and to look at the connection between them. RAL Space leads an ESA funded consortium that developed and built this instrument. The UK Space Agency contributed one of the subsystems to SPICE.

Mission facts:
The mission orbit is designed to be synchronous with the Sun’s rotation, providing long duration observations for the first time. This will enable the mission to observe the build-up of events such as solar storms.

The instruments on board will undertake remote sensing observations of solar features and in situ measurements of the solar wind bombarding the spacecraft. This combination of remote and in situ instruments will enable in-depth studies of the close link between the origin of solar features such as solar eruptions and their emergence into space. This unique mission could provide major breakthroughs in our understanding of how the inner solar system works and is driven by the solar activity.

The three-axis stabilised design of the spacecraft is being developed to withstand the scorching heat from the Sun that will hit one side and the cold of space on the opposite side which will usually be in shadow.

Solar Orbiter is managed and financed mainly by ESA with strong international collaboration with NASA as part of the International Living with a Star initiative.